The present invention relates to railway vehicle couplers and more particularly to an improved railway coupler head having a modified lock chamber.
Both AAR Type E and Type F railway couplers are known to have coupler heads with substantially horizontal top faces that transfer draft or pulling as well as buff or compression forces to corresponding top faces of coupler shanks. Further, both type coupler heads are known with lock chambers that project upwardly from these top faces and which have substantially vertical knuckle side walls which transfer draft and buff forces to the top faces of the coupler heads which then transfer these additional forces to the corresponding top faces of the coupler shanks. The transverse line at the rear of the lock chamber where the top face of the coupler head meets the top face of the coupler shank is known as the coupler horn line.
A problem with the coupler heads used currently is that the top face narrows drastically between an arcuate shaped edge of the knuckle side face and the lock chamber as the horn line is approached. This restricted width of the top face as well as a lock chamber configuration in which a knuckle side wall meets a rear horn wall abruptly at a radiused corner results in a high concentration of stress at the knuckle side of the horn line due to the forces being transmitted through the knuckle side of the top face and the knuckle side wall of the lock chamber which must, in turn, be transmitted across a significant width of the top face of the coupler shank. The stress concentration in the coupler head top face and the stress concentration in the lock chamber knuckle side wall are additive and are each at a near maximum at substantially the same location at the horn line. Due to the magnitude of these forces, a number of coupler failures have been experienced at the narrowed section of the top face at the horn line between the arcuate edge and the lock chamber.